Which compound is a simple sugar that circulates in the bloodstream and provides quick energy?

Which compound is a simple sugar that circulates in the bloodstream and provides quick energy?

• A. Starch
• B. Cholesterol
• C. Complex Carbohydrate
• D. Glucose

Answer: (D)

The main idea is identifying the molecule that acts as the body's quick energy source and travels in the blood. Glucose is a simple sugar, a monosaccharide, that circulates in the bloodstream as blood glucose. It can enter cells and be rapidly metabolized through glycolysis to produce ATP, providing quick energy. Starch and other complex carbohydrates are polysaccharides made of many glucose units. They must be broken down into simple sugars before the body can use them for energy, so they don’t circulate as a single simple sugar in the blood. Cholesterol is a lipid, not a sugar, and while it’s important for membranes and hormone production, it doesn’t deliver quick energy.

The main idea is identifying the molecule that acts as the body's quick energy source and travels in the blood. Glucose is a simple sugar, a monosaccharide, that circulates in the bloodstream as blood glucose. It can enter cells and be rapidly metabolized through glycolysis to produce ATP, providing quick energy.

Starch and other complex carbohydrates are polysaccharides made of many glucose units. They must be broken down into simple sugars before the body can use them for energy, so they don’t circulate as a single simple sugar in the blood. Cholesterol is a lipid, not a sugar, and while it’s important for membranes and hormone production, it doesn’t deliver quick energy.